Annotation Type DtoRef

@Target({FIELD,METHOD})
@Retention(CLASS)
public @interface DtoRef

Mark a DTO property as an id-only (or otherwise shallow) reference back to an already-visited type in the DTO graph, deliberately breaking what would otherwise be a cycle.

Used with generated entity-to-DTO graph mapping (see query.mapTo(SomeDto.class)). The DTO graph derived from a set of DTO types must form a DAG - generation fails at codegen time if it doesn't. @DtoRef is the explicit escape hatch for an intentional back-reference, e.g. a Contact DTO referencing its parent Customer by id only rather than re-embedding the full CustomerDto (which would recreate the Customer -> Contact -> Customer cycle):

public class ContactDto {
  int id;
  String firstName;
  String lastName;

  @DtoRef
  Integer customerId;   // id-only back-reference, no CustomerDto re-embedded
}

This is purely a compile-time / codegen-time hint - the DTO itself remains a plain, framework-free type with no runtime dependency on this annotation.

The association name (derived by stripping the Id suffix off the field/accessor name, e.g. customerId -> customer) must name a real, fetchable Ebean relation (one with a backing field) - if it's instead a computed/derived getter (e.g. a hand-written method picking one entry out of a collection, with no backing field of its own), its own data dependencies can't be inferred from the name alone, so requires() must explicitly name the real entity paths that need to be fetched for it to execute safely without triggering a lazy load:

@DtoRef(requires = "contacts")
Integer primaryContactId;   // getPrimaryContact() derives its result from contacts

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element	Description
String[]	requires	Real entity paths (dot-notation) that must be fetched to support a computed/derived association getter - required whenever the association name has no backing field, since its data dependencies can't otherwise be inferred.

Element Details

requires

String[] requires

Real entity paths (dot-notation) that must be fetched to support a computed/derived association getter - required whenever the association name has no backing field, since its data dependencies can't otherwise be inferred. Ignored (and unnecessary) when the association names a real, fetchable relation.

If the computed getter genuinely needs nothing extra fetched, set requires = {} explicitly to confirm that - as opposed to omitting requires entirely, which is treated as "not yet considered" and fails the build with a clear compile error.

Default:

{}